This study is designed to examine the historical demography and genealogies of the Utah Mormon population over a period of approximately 125 years, using materials which have been abstracted from the Genealogical Department of the Church of Jesus Christ of Latter-day Saints. Funds have been received (NCI Research Grant 16573) for the construction of the genealogies for Utah by linking all Mormon families whose children were born in Utah (or along the pioneer trail) to form a statewide genealogy which extends from 1830 to the present. The purpose of this grant is to provide the incremental funding to allow us to study the social, genetic, and historical demography of this population. The goals are to study the following aspects of the Mormon genealogies: 1. Basic demographic structure and changes; 2. Factors affecting marriage patterns and trends; 3. The prevalence of polygamy and its relationship to community structure; 4. Levels and trends of fertility measures; local variations; 5. The natural fertility reproductive process and the change to population control; 6. Mortality rates, trends, and life tables; 7. Migratory and settlement patterns of the pioneers; 8. Specific communities to explain local variations; 9. Inheritance of demographic traits with biological underpinnings; 10. Familial correlations in marriage and migration patterns; 11. Genetic demography emphasizing genealogical structure; 12. Trends and biological factors in the sex-ratio of birth.